1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device.
2. Description of Related Art
In a conventional semiconductor integrated circuit device which is used for an LCD (Liquid Crystal Display) driver, a semiconductor chip is directly connected, through a metal bump, on a glass substrate (which is called “LCD substrate” hereinafter), on which an LCD is mounted. FIG. 8 shows a plan view of an LCD substrate 1000, on which an LCD panel 1001 and a semiconductor integrated circuit device 1002 for use in an LCD driver are mounted. As shown in FIG. 8, in general, the semiconductor integrated circuit device 1002 for use in an LCD driver is mounted near the LCD panel 1001 where it is exposed to outside light. Therefore, the semiconductor integrated circuit device 1002 for use in an LCD driver may be directly or indirectly irradiated by outside light.
Meanwhile, as shown in FIG. 8, the semiconductor integrated circuit device 1002 for use in an LCD driver may contain a program circuit 1003 (which is called “PROM area” hereinafter) having a PROM (Programmable Read Only Memory). The PROM area 1003 can be used by a set maker, i.e., customer, to write set maker data (customer data) such as an arbitrary ID number. In such situation, the PROM is required to retain the written data. However, if the semiconductor integrated circuit device 1002 for use in an LCD driver is exposed to outside light, the outside light may irradiate the PROM area 1003 and erase the customer data recorded in the PROM. Therefore, the PROM area 1003 needs to be shielded from the light.
Accordingly, Japanese Unexamined Patent Application Publication No. 2006-154317 describes a display device in which a shield member is arranged over EPROM (Erasable Programmable Read Only Memory) mounted on an LCD substrate. Furthermore, Japanese Unexamined Utility Model Application Publication No. 05-038915 describes a technique in which a shield film is arranged over an EPROM memory cell on a semiconductor integrated circuit to cover the EPROM. Furthermore, Japanese Unexamined Patent Application Publication No. 07-066378 describes a technique in which a shield film having an exposure window over EPROM is provided, so that an operation threshold, of the transistors in the EPROM, which may be deteriorated during the formation process of the shield film, can be recovered by radiating ultraviolet light through the exposure window. Incidentally, the exposure window is covered by a light-blocking insulating film after the recovery of the operation threshold of the transistors in the EPROM. Furthermore, Japanese Unexamined Patent Application Publication No. 2003-124363 describes a technique in which a shielding film is arranged over EEPROM (Electronically Erasable and Programmable Read Only Memory). In addition, a contact plug and a via plug are also arranged around the EEPROM area to prevent outside light from being radiated from the lateral side of the EEPROM area.
However, in the above-explained semiconductor integrated circuit device in the related art, the PROM is shielded by the shield film, and the like, when the PAD portion is formed. Therefore, once a writing test is carried out for the PROM through the PAD portion, the written data cannot be erased by irradiating ultraviolet light to the PROM. Accordingly, in a semiconductor integrated circuit device in the related art, the writing test of a PROM cannot be carried out during the manufacturing process.
Therefore, a PROM mounted in a semiconductor integrated circuit device in the related art can only be used as a one-time programmable device (which is called “OTP device” hereinafter). As explained above, since a writing test of a PROM is not carried out in a semiconductor integrated circuit device in the related art, more than required number of PROMs (OTP devices) need to be formed in the semiconductor integrated circuit device. Because it contains more than required number of PROMs (OTP devices), even if one PROM (OTP device) is defective, another PROM (OTP device) can substitute for the defective one.
However, the total number of IDs required by a customer has been increasing, and sometimes it reaches to several hundred to several thousand bits Depending on defective rate, several ten to several hundred bits of PROMs (OTP devices) need to be formed in a semiconductor integrated circuit device. Consequently it has become an obstacle to the miniaturized design of semiconductor integrated circuit device.